X-ray Fluoresence Research Articles

ANALISIS PROVENANCE BATUPASIR FORMASI DOLOKAPA KABUPATEN GORONTALO UTARA BERDASARKAN DATA GEOKIMIA XRF

The research location is located in Deme 1 Village, East Sumalata District, North Gorontalo Regency. The rock outcrops studied are sandstones which are part of the Dolokapa Formation which is spread in the northern part of the Tilamuta Sheet. This study aims to analyze the tectonic setting of the origin of the sandstones. The research method used to achieve the research objectives is using two methods consisting of field geological surveys and X-Ray Fluoresence (XRF) Geochemical laboratory analysis. Based on the results and discussion that the two sandstone samples are of the Fe-Shale and Fe-Sand types which originate from the ARC (oceanic island arc) tectonic setting.

The Concentration of Heavy Metals Cd, Hg, Pb in Processed Food Products Based Pterygoplichthys pardalis (Castelnau, 1855) from Ciliwung River Jakarta Region

Backgrounds: Heavy metal that pollutes the river area affects living organisms which reside in it. Contamination of heavy metal in Ciliwung River leads to the presence of heavy metal elements (Cd, Hg, and Pb) inside the body of the plecos (Pterygoplichtys Pardalis) which inhabits that area. Hence, the utilization of plecos flesh and bones as a raw material in processed food products (e.g. shredded fish, shumai, and fish flour) might be harmful for human. Accumulated load of heavy metal in human's body would likely trigger health problems. Insufficient data on heavy metal concentration in Ciliwung River plecos-based food products underlies this research, with the aim to calculate the concentration of heavy metal Cd, Hg, and Pb on the previously mentioned plecos-based shredded fish, shumai, and flour. Methods: Heavy metal Cd, Hg, and Pb concentration analysis using X-Ray Fluoresence (XRF) methods conducted on PAIR Batan. Results: Value of Cd on shredded fish <0.5 mg/kg, shumai 0,7 mg/kg, head+tailbone and body skeleton flour <0.3 mg/kg. Value of Hg on shredded fish and shumai <0.7 mg/kg, head+tailbone flour 0.3 mg/kg, body skeleton flour 0.4 mg/kg. Value of Pb on shredded fish 1.3 mg/kg, shumai 0.8 mg/kg, head+tailbone flour 2.3 mg/kg, body skeleton flour 1.6 mg/kg. Conclusions: Heavy metal concentration on Ciliwung River plecos-based processed food products (shredded fish, shumai, and flour) has exceed maximum limit of Cd, Hg, and Pb determined by SNI, BPOM, and FAO.

UJI PARAMETER KIMIA BATU GAMPING SEBAGAI BAHAN BAKU SEMEN PADA LOKASI PENAMBANGAN CV THIAK KELURAHAN ARDIPURA KOTA JAYAPURA

Limestone mining owned by CV Thiak, which is located in the Ardipura II Jayapura city, has been operating for a long time. However, the utilization of limestone is only used as a mixed material in construction such as offices, schools, brdges and others. One sample of the use og limestone is a raw material for making cement. This study aims to determine the chemical content of limestone belonging to CV Thiak so that it can also be used as a raw material for making cement. The research stage is at the beginning with initial of reaserch location and mapping to determine the coordinates of the sampling location. Samples were taken at two different locations. Next, the stage of taking limestone as a sample for testing. The next stage is the description of the limestone to determine of type of limestone. The stage of sending limestone samples to the Mineral Engineering Laboratory in Bandung city to determine the chemical content contained in the sample. The last stage is the analysis of chemical parameters as data from laboratory test using the X-Ray Fluoresence method. Some of the chemical parameters analyzed were CaCO3, CaO, MgO, Al2O3, Fe2O3 and SiO2. From the results of the analysis, it is known that the two limestone sample belonging to CV Thiak have very high CaCO3 content. The CaCO3 at the first point has a level of 98,78 %. Meanwhile, the sample at the second point has a CaCO3 content of 98,38 %. For levels of CaO, the first point is 55,35 % and the second point is 55,13 %. By looking at the value of the content of CaCO3 and CaO, the quality of CV Thiak’s limestone is very good and meets the standars as cement raw materials, according to Portland cement standards

CHARACTERIZATION OF MAGNETIC PROPERTIES OF IRON SAND PUNTARU BEACH, ALOR REGION-NTT

Iron sand is a source of natural magnetic material which is quite abundant. Iron sand can be useful as a magnetic source material which has the potential as a raw material for using magnetic materials. Iron sand contains non magnetic minerals which can reduce its magnetic properties. Therefore, iron sand sample preparation was carried out by washing NaOH 0,4 M and sand sample size variations. The purpose of this study was to determine the effect of washing and the size of iron sand on the magnetic properties in terms of the increase in magnetic elements. The results of research with XRF (X-Ray Fluoresence) show that iron sand with a size of 120 mesh has a magnetic content of Fe (78.07%) higher than iron sand with a size of 80 mesh with Fe content (34.63%). XRD (X-Ray Diffraction) analysis shows that washing iron sand with a size of 80 mesh gives a quarts phase (SiO 2 ) at 2θ = 27.62° and iron sand washing with a size of 120 mesh gives the main peak magnetite phase (Fe 3 O 4 ) at 2θ = 30.69° with a crystallinity of 15%. VSM (Vibrating Sample Magnetometer) analysis depicted on the hysteresis curve shows that the smaller the particle size of iron sand, the higher the magnetic properties. There are still minor oxides in iron sand as oxide minerals.

Chemical Characterization of Harmattan Dust across Oyo and Minna, Nigeria

Harmattan dust haze in Nigeria is due to annual deposition of very fine dust particles as a result of both natural and human activities. There are scanty reports on the mineralogical, elemental and heavy metal composition in the Harmattan dust blowing across the country to support the presence of minerals and elements in the Harmattan dust. The aim of this study is to assess minerals and elemental compositions of Harmattan dust variations across Oyo (7032'N, 3025'E) and Minna (9035'N, 6032'E), Nigeria. Harmattan dust samples were collected using clean plastic bowls of 10 cm diameter and analysis was conducted on the samples collected at the two stations using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Fluoresence (XRF), Particle Induced X-ray Emission (PIXE) and Atomic Absorption Spectroscopy (AAS). It was observed that elements, such as K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Mo, As, Zr, Pb, V, Sr, Cr and Ce, were present in different concentrations in the samples collected. Minerals, such as Quartz [SiO2], Rutile [TiO2], Periclase [MgO], Corundum [Al2O3], Hematite [Fe2O3], Cuprite [Cu2O], Baddeleyite [ZrO2], Litharge [PbO], Monazite [P2O5], Zincite [ZnO], Montroydite [HgO] and Lime [CaO], were present in the samples collected at each station in different proportions. The soil mass concentration of the elements was calculated and observed to be 3.5179μg m3 at Oyo and 3.4745μg m3 at Minna. It was observed that the Harmattan dusts moving across Nigeria have almost all the elements present in Harmattan dust varying from station to station as the dust is moving towards the south of the country. The study concluded that the elemental composition of the dust samples analyzed revealed that the percentage compositions of some elements are higher than the acceptable WHO standard values, which may affect human health. It is therefore recommended that adequate precautionary measures and policies should be made to help mitigate the effects of high elemental concentrations observed.

Application of nuclear analytical techniques to assess air quality in Indonesia

Air pollution has become a global concern because of its effects on the environment and human health. Nuclear analytical techniques (NATs) have important application in air pollution monitoring and research. NATs such as Instrumental neutron activation analysis (INAA), Particle Induced X-ray Emission (PIXE), X-ray fluoresence (XRF), and X-ray absorption near-edge structure (XANES) have been used in quantification of environmental pollutant especially airborne particulate samples (APM) collected from several cities in Indonesia. The samples were analysed for elemental concentrations by INAA at Siwabessy multipurpose reactor and Bandung TRIGA 2000 reactor in Indonesia, PIXE at Institute of Geological and Nuclear Sciences New Zealand, XRF at BATAN Bandung Indonesia, and Synchrotron facilities at Elettra Italy. The techniques provide more than 20 significant elements for identification the possible sources of atmospheric aerosol. The results demonstrated that INAA, PIXE, XRF and XANES can complement significantly the elemental characterization of APM providing the concentration of several major, minor and trace elements. These results can be used as important information on levels and sources of air pollution. It could also be used as an early warning, scientific research-based references in designing and revising various government policies and regulations related air quality standards in Indonesia.

The Correlation Between Heavy Metal and Nutrient Content in Plecostomus (Pterygoplichthys pardalis) from Ciliwung River in Jakarta

Most of the rivers’ quality in Indonesia is in highly-polluted status including Ciliwung River in Jakarta. The pollution can affect river ecosystem especially the rivers biota such as plecostomus species that is mostly found in Ciliwung River. The information about correlation between heavy metal and nutrition content in Plecostomus flesh still limited, so the result from this research can give the new information about that. The aims of this research is identifying the effect of the heavy metals towards the contents of protein and fat of plecostomus flesh from Ciliwung River. The analyses methods use X-Ray Fluoresence (XRF) Spectrometer, the analysis of protein using kjeldahl method, and fat analysis using extraction method. The result of this research showed that small-sized plecostomus contained the highest fat and protein compared to medium-sized and big-sized plecostomus. The assumption was the contents of heavy metal which can impede protein and fat absorption. Meanwhile, the content of carbohydrate in small-sized plecostomus was the lowest. The identified type of heavy metal using XRF method was Pb, Hg and Cd with the concentration was higher than the maximum standard (SNI) so that the flesh of plecostomus from Ciliwung River in Jakarta is categorized unsuitable to consumption

Study on the Catalytic Effect of Nitric Acid Activated Myanmar Natural Clay for the Degradation of Plastic Wastes

In this study, the performance of different acid treated Myanmar Natural Clay (Mabisian) was conducted the pyrolysis of mixed plastic wastes, 40% high density polyethylene, 30% polypropylene, 25% low density polyethylene and 5% polystyrene. Mabisian clay was refluxed with different concentration of nitric acid (2M, 4M, 6M, 8M, 10M, 12M and 14M) at 100ºC for 3hrs followed by calcination at 500ºC for 1hr. The physico-chemical characteristics of resulted leached clay were studied by X-Ray Fluoresence spectroscopy (XRF), X-Ray Diffraction (XRD) and Fourier Transformed Infrared Spectroscopy (FTIR). The pyrolytic oil was characterized by Gas Chromatography – mass spectopy (GC-MS). XRF and FTIR studies indicated that acid treatment under reflux condition lead to the removal of octahedral Al3+ cations along with other impurities. The chemical treatment increased the Si/Al ratio. The maximum liquid yield (75%) was obtained at 12 M nitric acid, 3hr reaction time and 100 º C reaction temperatures. In addition, the percent peak area of gasoline range hydrocarbon was obtained 55.6% at optimum condition. Thus, the treated clay can be used as promising as catalyst support.

Study on the Catalytic Effect of Nitric Acid Activated Myanmar Natural Clay for the Degradation of Plastic Wastes

In this study, the performance of different acid treated Myanmar Natural Clay (Mabisian) was conducted the pyrolysis of mixed plastic wastes, 40% high density polyethylene, 30% polypropylene, 25% low density polyethylene and 5% polystyrene. Mabisian clay was refluxed with different concentration of nitric acid (2M, 4M, 6M, 8M, 10M, 12M and 14M) at 100ºC for 3hrs followed by calcination at 500ºC for 1hr. The physico-chemical characteristics of resulted leached clay were studied by X-Ray Fluoresence spectroscopy (XRF), X-Ray Diffraction (XRD) and Fourier Transformed Infrared Spectroscopy (FTIR). The pyrolytic oil was characterized by Gas Chromatography – mass spectopy (GC-MS). XRF and FTIR studies indicated that acid treatment under reflux condition lead to the removal of octahedral Al3+ cations along with other impurities. The chemical treatment increased the Si/Al ratio. The maximum liquid yield (75%) was obtained at 12 M nitric acid, 3hr reaction time and 100 º C reaction temperatures. In addition, the percent peak area of gasoline range hydrocarbon was obtained 55.6% at optimum condition. Thus, the treated clay can be used as promising as catalyst support.

Preparation and Characterization of SiO2/Co and C/Co Nanocomposites as Fisher-Tropsch Catalysts for CO2 Hydrogenation

To fabricate high-density cobalt-based catalysts, we first synthesized SiO2/C composites via a hydrothermal method and removed C and SiO2 by two different methods, respectively. The as-prepared SiO2 and C supports then reacted with cobalt acetylacetonate and N,N-dimethylformamide(DMF) under hydrothermal conditions to prepare SiO2/Co and C/Co nanocomposite catalysts. The catalysts were characterized by X-ray diffraction(XRD), scanning electron microscope(SEM), transmission electron microscopy(TEM), inductively coupled plasma mass spectrometry(ICP), energy dispersive X-ray fluoresence spectrometer(EDX), and nitrogen adsorption. It was found that hexagonal cobalt nanocrystals were successfully integrated with the mesoporous silica or carbon nanotube supports. SEM and TEM results show that SiO2/Co composites with a hollow/mesoporous sphere structure and C/Co composites with a tubular structure have been successfully synthesized. Both composite samples show superparamagnetism exhibiting an S-type hysteresis loop, which originated from the cobalt nanoparticles in the samples. Nitrogen adsorption/desorption curves suggest that the SiO2 and C supports have well-developed pore structures and large specific surface areas, and the loading and good dispersity of cobalt nanoparticles on the supports were proven by ICP and EDX. Moreover, the samples exhibited good and stable catalytic activity, demonstrating that the two composites are suitable catalysts for Fischer-Tropsch CO2 hydrogenation.

Effect of Curing Time and Sintering to the Properties of Geopolymer Mortars

In this study, the geopolymer mortars were synthesized with fly ash (FA) and silica powder as aluminosilicate sources and a combination of sodium hydroxide (NaOH) solution, sodium silicate (Na2SiO3) solution and distilled water as alkaline activator. Commercial sago was used as a pore former in the mortars. The percentage of sago used were 10, 20 and 30 wt% of FA. The amount of added water used in each mixture was 5% by weight of FA, NaOH solution and Na2SiO3 solution. The formed geopolymer mortars were cured for 1, 3 and 7 days and sintered at 1000 °C. X-ray fluoresence (XRF) shown that FA contains higher amount of silica (SiO2) and alumina (Al2O3) which is important as aluminosilicate sources. The properties of the geopolymer mortars before and after sintered at 1000 °C have been investigated. The results show that geopolymer mortars with 10% of sago content with curing time of 7 days and sintered at 1000 °C give the highest compressive strength of 13.5 MPa.

Mineralogical characterization of coal samples relevant to coal bed methane porosity and permeability concerns

Abstract Lower than anticipated gas production rates in coal bed methane (CBM) operations are sometimes related to formation damage in which reduced permeability results from the interaction of bore and fracturing fluids with coal. This study assesses the potential for mineral precipitation to cause formation damage from a Permian coal seam in the Bowen Basin, eastern Australia, using geochemical modelling of coal mineralogy, formation fluid and bore fluid composition. The mineralogical composition of coal was assessed using petrography, X-ray diffraction, X-ray fluoresence and electron beam microanalysis. Geochemical modelling of ambient groundwater and drilling fluid interactions with coal samples was undertaken using Geochemist's WorkBench (GWB). This modelling indicates that likely mineral precipitates/re-precipitates to adversely impact porosity and permeability include a range of clay, carbonate and sulphate minerals. Additionally, these interactions may induce alteration of precursor smectites to new species that reduce permeability. The resultant smectites also have a high propensity for expansion and dispersion in the presence of inappropriate drilling fluids. Precipitation, expansion and dispersion of these fine-grained minerals may potentially lead to large reductions in permeability, with profound impacts upon gas flow. Indications are that reduced permeability can be mitigated by suitable chemical matching of groundwaters with drilling fluids.

Structure and Ion Exchange Behavior of Zirconium Antimonates for Strontium

Zirconium antimonates with initial Sb:Zr mole ratios of 1.0, 1.5, 4.0, and 9.0 were synthesized by co-precipitation to remove strontium ions from acidic solutions. The characterization of materials was investigated by X-ray diffraction (XRD), Scanning electron microscopy-Energy dispersive X-ray (SEM-EDX), X-ray fluoresence (XRF), and zeta potential analyses. Ion exchange studies of the synthesized materials towards strontium were conducted as a function of contact time and initial pH. Preliminary results reveal that as the antimony ratio increases the surface of the materials become more acidic and thus, strontium exchange is more favorable in a pH range of 2-6.

Tin Oxide Doped on Activated Dolomites as Efficient Catalyst for Biodiesel Production

Activated dolomite (AD), was investigated as a promising heterogeneous catalyst for the production of biodiesel. SnO2 doped on activated dolomites catalyst (DSN) was synthesized through wet impregnation method and calcined at 500 °C for 3 h in air. The catalyst was then applied on biodiesel production via transesterification of palm cooking oil with methanol for required conditions (various time, oil to methanol ratio and amount of catalyst). X-ray Diffractometer (XRD), Brunauer-Emmet-Teller (BET) surface area, X-ray Fluoresence (XRF), Scanning Electron Microscopy (SEM) and Temperature Program Desorption (TPD) analysis were used to characterize the properties of the catalysts. Results showed that conversion of biodiesel by using DSN was higher (99.9 %) with lower optimum conditions i.e. 1:15 methanol to oil molar ratio, 1 wt. % of catalyst amount and reaction time of 6 h at 65 °C compared to AD (98.34 %) under higher conditions.

Effects of Calcination Temperature of LUSI Mud on the Compressive Strength of Geopolymer Mortar

The abundant availability of LUSI (a short form of LUmpur SIdoarjo or Sidoarjo mud) mud of a mud volcano located in Sidoarjo, East Java, Indonesia, attracts interest of researchers to seek the possibility of utilizing it; among them is as construction material. This study focuses on the effect of calcinations temperatures of LUSI mud on the compressive strength of geopolymer mortar. Three different calcinations temperatures were investigated, i.e. 700, 800 and 900°C for five hours duration. Characterization of the mud, both the original and the calcined ones, was performed by using X-ray Diffraction (XRD) and X-ray Fluoresence (XRF) analyses. The calcined LUSI mud was then employed as precursor for making geopolymer mortar, and tested for its 7-day compressive strength. It is found that calcinations at 800°C is the optimum calcinations temperature producing the highest compressive strength.

Micro Energy-Dispersive X-Ray Fluoresence Mapping of Enamel and Dental Materials after Chemical Erosion

Energy-dispersive X-ray fluorescence was employed to test the hypothesis that beverage consumption or mouthwash utilization will change the chemical properties of dental materials and enamel mineral content. Bovine enamel samples (n = 45) each received two cavity preparations (n = 90), each pair filled with one of three dental materials (R: nanofilled composite resin; GIC: glass-ionomer cement; RMGIC: resin-modified GIC). Furthermore, they were treated with three different solutions (S: saliva; E: erosion/Pepsi Twist®; or EM: erosion+mouthwash/Colgate Plax®). It was found that mineral loss in enamel was greater in GICE samples than in RE > RMGICE > RMGICEM > REM > GICEM. An increased percentage of Zr was found in REM indicating organic matrix degradation. Dental materials tested (R, GIC, and RMGIC) were not able to protect adjacent enamel from acid erosion by the soft drink tested. The use of mouthwash promoted protection of enamel after erosion by the soft drink. To avoid chemical dissolution by mouthwashes, protection by resin composites with surface sealants is recommended.

Optimization of Energy Dispersive X-Ray Fluorescence Spectrometer to Analyze Heavy Metals in Moss Samples

Problem statement: Mosses had been widely used as bioindicator especially to study the levels of trace metals pollutants in the surrounding ambient air because of their high efficiency to accumulate heavy metals contamination. There had been increasing demand to get a suitable analytical tools to determine the chemical contents of moss samples in this type of media. This study was conducted with the aims to get one of the best analytical methods for the analysis of moss samples. Approach: Despite the various spectroscopic techniques that normally used to analyzed heavy metals in moss, each of these techniques had its advantages and disadvantages which been summarized elsewhere. We try not to use any chemical to decompose the samples where the samples were analyzed directly in its solid form by Energy Dispersive X-Ray Fluoresence Spectrometer, EDXRF technique. The EDXRF technique optimized for its main analytical parameters. Calibration procedure was made based on the in-house standard samples. The reliability of the optimized analytical procedure was established by analyzing two certified reference materials, Pine Needle, NIST 1575 and Lichen, IAEA-336. Results: The results showed that the metals could be analyzed with percent recoveries range within 84-102% for Pine Needle and 92-125% for Lichen. The possible factors influencing the percent recoveries of the elements were discussed in details. Conclusion: On overall, it is strongly suggest that the applied EDXRF method is adequate enough to analysis the heavy metal contents in moss samples even at very small concentration with high accuracy and precisely.

PREPARATION, CHARACTERIZATIONS AND MODIFICATION OF Ni-Pd/NATURAL ZEOLITE CATALYSTS

Preparation, and modification of Ni-Pd/natural zeolite as well as their characterizations had been carried out. The aim of this research for the fututure is to prepare the best characters catalyst for the conversion of waste plastics fraction to gasoline fraction (C5-C12 hydrocarbons). The preparation of catalysts was performed by reacting a natural zeolite with the precursor of Ni(NO3)2. 9H2O and PdCl2 in an ammonia solution (25%). The modifications were performed by varying the rasio of Ni/Pd loaded to the zeolite, whereas the Pd was previously loaded and total metal content was 1 wt.% based on the zeolite. The characterization of catalysts included determination of acidity gravimetrically by adsorption of ammonia or pyridine vapour base method, metal content by Atomic Adsorption Spectrophotometer (AAS) and X-ray Fluoresence (XRF) and crystallinity by X-ray Diffraction (XRD). The treatment of catalysts using Etilene Diamine Tetra Acetic acid (EDTA) was performed to study the metal distribution on the outer or inner surface of the zeolite. The characterization results showed that the loading of metals to the zeolite increased its acidity and decreased its spesific surface area, however, did not defect its crystallnity. The metals loaded on the zeolite were distributed inside the pore and at outer surface of the zeolite. For all catalyst samples, the acidities determined using ammonia were higher than those of pyridine, and the acidities determined before the EDTA treatment was lower than those after the treatment. Metal contents of the zeolite before the EDTA treatment were higher than those after the treatment. The EDTA treatment enhanced the crystallinity of the sampel. The relationship between the metal rasio towards the acidity of the catalyst samples were in variation. Catalyst samples produced in this research have good characters, thus promisingly can be used for conversion process of waste plastics to gasoline fraction. Keywords: natural zeolite, acidity, metal content, crystallinity, EDTA

Fabrication of anatase titanium dioxide nanotubes by electroless deposition using polycarbonate for separate casting method

Abstract Titanium dioxide nanotubes (TNTs) were prepared by electroless deposition using ion track etched polycarbonate templates. The ion tracks were prepared to the desired diameter of the TNTs outer diameter. Titanium dioxide nanotubes with a diameter of minimum 80 nm having a wall thickness of minimum 10 nm can be fabricated using this method. To achieve nanotubes with thin walls and small surface roughness the tubes were generated by a several steps procedure under aqueous conditions at nearly room temperature. The presented approach will process open end nanotubes with well defined outer diameter and wall thickness. Using this method TNT arrays up to 109 tubes per cm2 having a tube length up to 30 μm can be produced, single tubes are also possible. The structural properties of the grown TNTs were investigated by using various analytical techniques, i.e. scanning electron microscopy (SEM), energy dispersive X-ray fluoresence spectrometer (EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy and Photoluminescence.

Hepatocellular transport and gastrointestinal absorption of lanthanum in chronic renal failure

Lanthanum carbonate is a new phosphate binder that is poorly absorbed from the gastrointestinal tract and eliminated largely by the liver. After oral treatment, we and others had noticed 2-3 fold higher lanthanum levels in the livers of rats with chronic renal failure compared to rats with normal renal function. Here we studied the kinetics and tissue distribution, absorption, and subcellular localization of lanthanum in the liver using transmission electron microscopy, electron energy loss spectrometry, and X-ray fluorescence. We found that in the liver lanthanum was located in lysosomes and in the biliary canal but not in any other cellular organelles. This suggests that lanthanum is transported and eliminated by the liver via a transcellular, endosomal-lysosomal-biliary canicular transport route. Feeding rats with chronic renal failure orally with lanthanum resulted in a doubling of the liver levels compared to rats with normal renal function, but the serum levels were similar in both animal groups. These levels plateaued after 6 weeks at a concentration below 3 microg/g in both groups. When lanthanum was administered intravenously, thereby bypassing the gastrointestinal tract-portal vein pathway, no difference in liver levels was found between rats with and without renal failure. This suggests that there is an increased gastrointestinal permeability or absorption of oral lanthanum in uremia. Lanthanum levels in the brain and heart fluctuated near its detection limit with long-term treatment (20 weeks) having no effect on organ weight, liver enzyme activities, or liver histology. We suggest that the kinetics of lanthanum in the liver are consistent with a transcellular transport pathway, with higher levels in the liver of uremic rats due to higher intestinal absorption.